The aim of the study was to set in order some ethic problems of scientists and practitioners in their activities bound with plant protection against agrophages. It touches the responsibility for the effects of applying different factors which modify the environment. The study describes basic research situations: of certainty, of risk and of uncertainty. Also, kinds of research plans were described: laboratory, semi-natural, natural. Connections between research situations and research plans were discussed. Additionally, legal regulations of European Union, concerning applying of plant protection products, were commented and products’ label on negative effects of using pesticides were criticized. Some more examples of ethic dilemma of a researcher and a practician were mentioned.